Plasticity

Elasticity vs Plasticity

• Material specimen loaded up to point $A$ then unloaded.
• If stress-strain curve is traced in reverse, the material is elastic.
• Point $E$ represents the transition point (Elastic Limit) beyond which the curve is no longer retraced as the specimen is unloaded.
  
• Unloading curve $BC$ is parallel to the initial portion of the loading curve (parallel to tangent to the loading curve at Point $O$)
• Characteristic by which material undergoes inelastic strains beyond the elastic limit is known as Plasticity.